The beach access track can be a bastard on a big and/ or loaded bike.
Definitely easier down than up. The sand is deep and lose with mixed-in rocks up to head-size and remnants of a former concrete/ asphalt ramp.
Add a steep 120degree bend to the mix, some deep sand berms on the bottom with a narrow strip of rocks and a trickle of a tiny spring making the rocks slippery.... and a few helping hands might be gladly appreciated to nurse the bikes down.
*** DEFINITELY walk the stretch first ***

<<<<<< Alternative to Aranga Beach access >>>>>> : Follow the SH12 Highway from the Kaihu Fuel station south towards Dargaville for ~4km and turn off to Omamari. Babylon Coast Rd/ Basin Rd. and Baylys Basin Rd. will lead into Baylys Beach for an easy access onto Ripiro Beach and on to Poutu. ONCE MORE: HEED THE TIDES!!! Map: https://goo.gl/e6GsCM